| Abstract: | The Analysis Committee has collaboratively tested local routine headspace gas chromatographic methods for the determination of the lower boiling point volatile compounds in beer. The repeatability values (r95) were dependent upon mean concentration (m) for acetaldehyde and alcohols but not for esters, whilst reproducibility values (R95) were dependent upon concentration in all cases. The range of values of m and the estimates of r95 and R95 (mg/litre) for each compound were, respectively: acetaldehyde (5–8, 0.21m, 0.60m); propanol (9–23, 0.25m, 2.5+0.57m); isobutanol (5–22, 0.56+0.085m, 1.7+0.15m); methylbutanols (45–105, 0.14m, 0.22m); ethyl acetate (10–54, 3.1, 2.1+0.29m); isoamyl acetate (0.8–4.7, 0.36, 0.20+0.58m); and ethyl hexanoate (0.13–0.36, 0.073, 0.10+0.91m). No advantage was gained by diluting beer samples containing 9% V/V ethanol to 4% ethanol (used for the calibration mixtures) prior to analysis, but use of a standard method of sample preparation decreased most of the R95 values. No recommendation is made in this interim report. |
